Not render sky texture?
Blender Internal:
Method 1:
You could disable Sky in Properties &gt; Render Layers &gt; Layer:

With Sky enabled:

With Sky disabled:

Method 2:
Another way is to set the Alpha to Transparent in Render settings &gt; Shading:

This will give the same result as disabling Sky in Render layers &gt; Layers.
Cycles:
For cycles you could set the Film to Transparent in Render settings &gt; Film:

With Transparent disabled:

With Transparent enabled: